11. New Insights into Manganese Local Environment in MnS-1NanocrystalsAlenka Ristić, Matjaž Mazaj, Iztok Arčon, Nina Daneu, Nataša Zabukovec Logar, Roger Glaser, Nataša Novak Tušar, 2019, original scientific article Abstract: Manganese plays an important role in redox catalysis using zeolites as inorganic support materials, but the formation of the preferred redox manganese species (framework or extraframework) is still not well understood. Herein, the influence of the amount of manganese together with conventional and microwave-assisted hydrothermal synthesis paths on the formation of manganese species within the zeolite silicalite-1 (S-1) with MFI structure was investigated. It was found out that both synthesis procedures led to the formation of framework and extraframework manganese species, but in different molar ratios. However, the conventional synthesis procedure with all Mn/Si molar ratios generates more framework Mn in comparison to the microwave procedure. Additionally, the diminution of the zeolite crystals to nanoscale from 100 to 200 nm was achieved via the conventional procedure for the first time. UV–vis, Raman, and X-ray absorption spectroscopic analyses revealed different local environments of manganese: Mn3+ incorporated into the silicalite-1 framework as “framework manganese” and Mn2+/3+ present as “extraframework manganese” (Mn2O3, Mn3O4). TEM reveals the presence of Mn3O4 nanorods. Both framework manganese and extraframework manganese exhibit good catalytic activity for styrene epoxidation. Catalytic results suggest that, in oxidation reactions of hydrocarbons, framework manganese is more active at lower Mn contents (Mn/Si < 0.015), whereas extraframework manganese is more active at higher loadings (Mn/Si > 0.015).
Keywords: MnS-1 Nanocrystals, Mn XANES, EXAFS, zeolites, microwave-assisted hydrothermal synthesis
Published in RUNG: 06.05.2019; Views: 3431; Downloads: 0
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12. Cu and Zr surface sites in photocatalytic activity of TiO [sub] 2 nanoparticles : the effect of Zr distributionOlena Pliekhova, O. L. Pliekhov, Mattia Fanetti, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2019, original scientific article Abstract: The present work is focused on the role of ZrO2 modification in the performance of CuO modified TiO2. Zirconia
loading leads to formation of more resistant photocatalytic layers compared to samples modified with only
copper containing species. Surface modification of mixed phase TiO2 with CuO/ZrO2 improves the degradation
of Reactive blue 19 dye under simulated solar irradiation. An in-depth investigation of the catalysts showed that
in case of CuO/ZrO2 modification, the covering of the TiO2 surface with zirconium containing species prevents
morphological and harmful energetic changes induced by copper species formed on the rutile TiO2 phase at a
higher copper loading.
Keywords: titanium dioxide, surface modification, XAS analysis, surface acidity, Hammett indicators
Published in RUNG: 26.03.2019; Views: 3227; Downloads: 0
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17. MOŽNOSTI ZMANJŠANJA ODPADKOV HRANE V SLOVENIJI: PRIMER MLEČNIH IZDELKOVBoštjan Gerbec, 2018, master's thesis Abstract: V magistrskem delu smo obravnavali problematiko zavržene hrane v Slovenji ter širše. V Sloveniji vsako leto zavržemo 73 kilogramov hrane na prebivalca, podatki zadnjih let pa kažejo na naraščanje teh količin. Polovico zavržene hrane ustvarijo gospodinjstva. Ker je hrana nepogrešljiva za življenje, veliko ljudi pa živi v pomankanju, je takšno stanje zaskrbljujoče in nas kot družbo ne prikazuje v najboljši luči.
Pri razumevanju problema in pri iskanju rešitev smo poleg pregleda zakonodaje in znanstvene literature izvedeli tudi raziskavo na primeru mlečnih izdelkov. Uporabili smo tri raziskovalne pristope: anketo, intervju ter eksperiment s preizkusom izdelka. Ugotovili smo, da je literatura v večini dostopna le v obliki znanstvenih člankov in študij, prav tako še do nedavnega ni bilo sistematičnega zbiranja in vodenja evidenc o količinah zavržene hrane. V nalogi smo predlagali ukrepe in načine, kako bi lahko zmanjšali količino zavržene hrane, in izpostavili velik pomen tega, da vsak posameznik začne pri sebi. Ustrezno je treba nakupovati hrano, planirati obroke ter hrano tudi pravilno shranjevati. V nalogi smo tudi predstavili različne primere dobrih praks, ki prav tako pomagajo zmanjševati količino zavržene hrane, bodisi v Sloveniji bodisi v tujini.
V nalogi smo potrdili hipotezo, ki smo jo izpostavili na začetku, da se lahko količina zavržene hrane v Slovenji zmanjša. Potrošniki lahko na to neposredno vplivamo v domačih gospodinjstvih. S spremembami nakupovalnih navad pa lahko v določeni meri vplivamo tudi na trgovce in na njihovo ponudbo živil. Na problem hrane, ki se izgublja v proizvodnem in distribucijskem delu življenjskega cikla, pa v širšem smislu lahko vplivajo tako vlade vseh držav kot tudi mednarodna skupnost.
Keywords: zavržena hrana, zakonodaja, gospodinjstva, primer zavrženih mlečnih izdelkov, zmanjševanje odpadne hrane z ozaveščanjem, zmanjševanje odpadne hrane z državnimi politikami
Published in RUNG: 14.09.2018; Views: 4526; Downloads: 182
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19. The effect of Zr loading on photocatalytic activity of Cu modified TiO2Olena Pliekhova, O. L. Pliekhov, Mattia Fanetti, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2018, published scientific conference contribution Keywords: Titanium diokside, acidic sites, surface titration, copper, zirconium
Published in RUNG: 10.09.2018; Views: 3935; Downloads: 0
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20. Surface modified titanium dioxide using transition metals : nickel as a winning transition metal for solar light photocatalysisAndraž Šuligoj, Iztok Arčon, Matjaž Mazaj, Goran Dražić, Denis Arčon, Pegie Cool, Urška Lavrenčič Štangar, Nataša Novak Tušar, 2018, original scientific article Abstract: Titanium dioxide has been widely used as an antimicrobial agent, UV-filter and catalyst for pollution abatement. Herein, surface modifications with selected transition metals (Me) over colloidal TiO2 nanoparticles and immobilization with a colloidal SiO2 binder as composite films (MeTiO2/SiO2) on a glass carrier were used to enhance solar-light photoactivity. Colloidal TiO2 nanoparticles were modified by loading selected transition metals (Me ¼ Mn, Fe, Co, Ni, Cu, and Zn) in the form of chlorides on their surface. They were present primarily as oxo-nanoclusters and a portion as metal oxides. The structural characteristics of bare TiO2 were preserved up to an optimal metal loading of 0.5 wt%. We have shown in situ that metal-oxo-nanoclusters with a redox potential close to that of O2/O2 were able to function as co-catalysts on the TiO2 surface which was excited by solar-light irradiation. The materials were tested for photocatalytic activity by two opposite methods; one detecting O2 (reduction, Rz ink test) while the other detecting OH (oxidation, terephthalic acid test). It was shown that the enhancement of the solar-light activity of TiO2 by the deposition of transition metal oxo-nanoclusters on the surface depends strongly on the combination of the reduction potential of such species and appropriate band positions of their oxides. The latter prevented excessive self-recombination of the photogenerated charge carriers by the nanoclusters in Ni and Zn modification, which was probably the case in other metal modifications.
Overall, only Ni modification had a positive effect on solar photoactivity in both oxidation and reduction reactions.
Keywords: surface modified TiO2, XANES, EXAFS, Nickel, solar light photocatalyst
Published in RUNG: 01.06.2018; Views: 3544; Downloads: 0
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